The present invention relates generally to the field of motors for use with sensors such as resolvers and encoders. More specifically, the present invention relates to the design of an encoder that is readily useful with a motor that was designed for use with a resolver.
Many motors, e.g., brushless DC servomotors, were previously designed to include a resolver. A resolver is useful to provide position and velocity information of a rotor for the motor. This information is used by external electronics to control the velocity and position of the rotor.
Somewhat recently, the use of encoders instead of resolves has become more prevalent. While not appropriate for all applications, encoders have been found to generally have better performance than a resolver. However, the use of an encoder typically requires that the end bell of the motor be modified so as to receive the encoder Instead of the resolver. The change in the end bell is required because the physical size and mounting footprint of the encoder is generally not compatible with the design of a motor for use with a resolver. A change to the end bell of the motor is therefore required if an encoder is to be used in place of a resolver. Accordingly, manufactures are required to keep in inventory different parts in order to accommodate the use of a resolver or encoder thereby increasing the cost of manufacture. Also, the assembly of motors with different sensors requires the use of different processes which thereby increases the time required for manufacture.
Therefore, there is a need for a motor assembly that can readily accommodate either a resolver or an encoder without the use of additional parts and assembly processes.
The present invention is directed to a motor assembly that can readily accommodate either a resolver or an encoder. More specifically, the preferred embodiment of the present invention is directed to an encoder that is useful with a motor designed for use with a resolver.
According to a first aspect of the invention, a motor that can interchangeably accommodate a resolver or an encoder is provided. The motor includes a housing having a top portion with a curved recess located therein. A rotatable shaft extends from the recess of the housing. A connector adjacent the shaft is adapted to fit within the recess of the housing. An encoder is connected to the connector and is adapted to allow the shaft to pass therethrough. Accordingly, a motor is provided that may interchangeably accommodate a resolver or an encoder.
According to a second aspect of the invention, an encoder assembly for use with a motor is provided. The motor has a top surface with a curved recess located therein. A rotatable shaft extends outward from the top surface of the motor. The encoder includes a ring-shaped connector adapted to fit within the recess of the housing. An encoder body is connected to the ring-shaped connector and is adapted to allow the shaft to pass therethrough. A single fastening is adapted to secure the encoder to the motor.
According to a third aspect of the invention, a method of assembling a motor having a sensor is provided. The method includes the step of providing a motor adapted to accommodate one of a resolver and an encoder. The method also includes the step of providing the other of the resolver and the encoder adapted to be used interchangeably with the one of the resolver and the encoder. Accordingly, a motor having a single configuration is useful with either of a resolver or encoder.
The use of the term xe2x80x9cencoder(s)xe2x80x9d is intended to be interpreted broadly to Include different types of encoders such as optical, magnetic or capacitive.